The present invention relates to an apparatus and method for use in handling sheet material articles and more specifically to an apparatus and method for feeding sheet material articles from a hopper.
Known devices for feeding sheet material articles from a hopper are disclosed in U.S. Pat. Nos. 3,650,525 and 3,702,187. These devices include a suction applicator head which is pivotally mounted beneath the hopper. The suction applicator head is movable to pull an edge portion of a lowermost sheet material article downwardly toward a rotating separator disk. The rotating separator disk engages the sheet material article and deflects it toward a feed drum. The feed drum pulls the sheet material article from the hopper and deposits the sheet material article onto a collator conveyor.
Due to the location of the suction applicator head relative to the hopper and the separator disk, the suction applicator head cannot be raised to engage a next succeeding sheet material article until the feed drum has pulled the preceding sheet material article past the suction applicator head. During rotation of a feed drum having a pair of grippers, as shown in U.S. Pat. No. 3,650,525, it takes about 30.degree. of movement of the feed drum to raise the suction applicator head. About the same duration, that is, about 30.degree., is required for the suction applicator head to pull the sheet material article downward for engagement by the separator disk. A short 15.degree. dwell time is provided to allow the suction applicator head to seal against the lower side of the sheet material article in the hopper. After the sheet material article has been pulled downward by the suction applicator head, the separator disk can enter over it to hold the sheet material article in position for engagement by grippers on the feed drum.
During movement of the suction applicator head into and out of engagement with a sheet material article, the portion of the feed drum circumference adjacent to the suction applicator head cannot be used to carry a sheet material article. The time required to move the suction applicator upward into engagement with the sheet material article, to seal against the lower side of the sheet material article, and to pull the sheet material article downward and for the separator disk to engage the sheet material article is a substantial portion of a revolution of the feed drum. This means that only a substantially reduced portion of the feed drum circumference can be used to carry a sheet material article.
It is desirable to have a sheet material article deposited on a raceway/track of a collator conveyor at a velocity and in a direction which matches the velocity and direction of movement of sheet material articles by the collator conveyor. In order to match the velocity between the feed drum and the collator conveyor, a track pusher chain division which is 30% to 40% greater than the signature length has been required. The distance by which a pusher chain division exceeds the signature length must be the same as the feed drum circumference which is required to accommodate movement of the suction applicator head.
In order to retain matched sheet material feed speeds by the feed drum and the collator conveyor, the timing of the collator conveyor and the feed drum becomes critical. This can result in an undesirable timing relationship between the feed drum and the collator conveyor, a large mismatch in the velocity at which sheet material is fed from the feed drum and the velocity at which feed material is moved by the collator conveyor, and/or a longer than desired distance between pusher chain centers on the collator conveyor.